Automatic transmissions for motor vehicles that are known in practice possess multiple shifting elements, whereas, in each gear of the automatic transmission, a first number of shifting elements is closed or switched on, and a second number of shifting elements is opened or switched off. For opening and closing, the shifting elements of the automatic transmissions known in practice are hydraulically actuatable, i.e. typically in such a manner that if, at a particular shifting element, no hydraulic pressure or hydraulic pressure that is too low is applied, the particular shifting element is opened, whereas if, at the shifting element, a sufficiently high hydraulic pressure is applied, the particular shifting element is closed.
Automatic transmissions with such hydraulically actuatable shifting elements are known, for example, from DE 10 2007 055 808 A1 and DE 10 2008 000 429 A1.
Interlocking hydraulically actuatable shifting elements of an automatic transmission in a closed state by means of a locking device or an interlocking device is also known from, for example, DE 102 44 523 A1, such that the respective shifting element also remains closed if the hydraulic operating pressure is released.
A hydraulically actuatable shifting element of an automatic transmission with a mechanical locking device or interlocking device is known from DE 103 04 050 A1.
A hydraulically actuatable shifting element of an automatic transmission with an electromotive or electromagnetically actuatable blocking device or interlocking device is known from EP 1 995 484 B1.
As stated above, if a hydraulically actuated shifting element is interlocked in a closed state by means of an interlocking device or a blocking device or a locking device, the particular shifting element is held in a closed state if the hydraulic operating pressure that is actually required for closing the particular shifting element is released. This has the advantage that the receiving torque of an oil pump, which is used to provide hydraulic operating pressure, can be reduced, such that the consumption of the motor vehicle may ultimately be reduced.
If a shifting element of an automatic transmission is interlocked, the interlocking must be lifted for the opening of the same; this is why it is necessary to open the respective interlocking device. Thereby, upon the opening of a previously interlocked shifting element, delay times may develop; these may affect the shifting dynamics of the automatic transmission.
There is a need for a method for operating an automatic transmission of a motor vehicle, with the assistance of which the interlocking for interlockable shifting elements of the automatic transmission may be selectively permitted or not permitted, and thus selectively activated or deactivated.